• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.43-54
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• 1996

This paper presents new heuristic search algorithms for searching rectilinear r(L1), link metric, and combined shortest paths in the presence of orthogonal obstacles. The GMD(GuidedMinimum Detour) algorithm combines the best features of maze-running algorithms and line-search algorithms. The SGMD(Line-by-Line GuidedMinimum Detour)algorithm is a modiffication of the GMD algorithm that improves efficiency using line-by-line extensions. Our GMD and LGMD algorithms always find a rectilinear shortest path using the guided A search method without constructing a connection graph that contains a shortest path. The GMD and the LGMD algorithms can be implemented in O(m＋eloge＋NlogN) and O(eloge＋NlogN) time, respectively, and O(e＋N) space, where m is the total number of searched nodes, is the number of boundary sides of obstacles, and N is the total number of searched line segment. Based on the LGMD algorithm, we consider not only the problems of finding a link metric shortest path in terms of the number of bends, but also the combined L1 metric and Link Metric shortest path in terms of the length and the number of bands.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.81-82
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• 2007

자율이동로봇을 위한 새로운 경로 계획 방법을 제안한다. 실시간으로 장애물을 피하고, 목표 지점까지의 최단 경로를 생성하여 유용성을 극대화시키기 위하여 방법을 다룬다. 본 논문에서는 효율적인 경로 계획방법으로 초기 경로를 생성하고, 생성된 경로를 개선하는 방법을 제안한다. 초기 경로는 그래프 기반 방법인 골격선 그래프와 탐색방법으로 딕스트라(Dijkstra) 알고리즘을 사용한다. 초기 경로에 대해 동적 프로그래밍 알고리즘을 이용하여 최단거리에 가깝게 경로를 개선한다. 시뮬레이션을 통해 제안하는 방법의 성능을 검증한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.777-780
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• 2020

본 논문은 동일 목적지를 가진 다수의 사람들이 동일 이동 수단을 탑승하여 이동할 경우 발생하는 소요 시간의 감소를 위한 거점 군집에 대해 다루려 한다. 실제 도로망에서는 노드에 해당하는 사람들의 위치가 유동적으로 변화 하고 사람 간의 거리 값 또한 변화하게 된다. 따라서 동일한 목적지를 가진 다수의 사람들이 한 대의 차량을 탑승하여 이동한다고 가정할 때 차량의 최단 경로 및 소요 시간 감소를 목적을 기반으로 설계하였다. 차량의 최단 경로를 감소시키 위해서 사람들을 군집화 하는 방법을 사용하였고 그 결과 경유지가 감소 되어 차량의 이동 경로 값은 감소되었다. 또한, 전체 이동 소요 시간 역시 군집을 통해 감소시킬 수 있다. 본 논문에서는 이와 같이 군집을 이용한 최단 경로의 감소와 전체 이동시간 감소에 대한 알고리즘을 설계하고 구현하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.193-205
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• 2011

This paper suggests $p$-facility locations in $m$ candidate locations and $n$ areas in optimal cost side(population${\times}$shortest distance). This problem has been classified by NP-complete because there is not a polynomial time algorithm. In this paper, we suggests reverse-delete method that deletes a candidate facility one by one from $p=m$ until $p=2$. As a result of the proposed algorithm for the $5{\times}5$ and $7{\times}7$, the initial solution is obtained. For the Swain's 55-node network, we obtain the optimal solution through a solution improvement process with $p=4$ and it by using the initial solution with $p=5$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.117-123
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• 2023

There are casualties due to inundation and flooding due to intensive typhoons or heavy rains in summer. Due to such damage, the biggest disaster is flood, and in order to reduce human damage, this paper proposes a shortest distance algorithm-based pedestrian path search study using Map API. This system selects Map API through comparative analysis and provides the shortest route. The route explored is in JSON format and the data of the shelter is stored in the database. The route search system designed and implemented based on this data locates pedestrians and provides evacuation routes in case of flash floods. In addition, if the route cannot be entered while moving to the evacuation route, the current location of the pedestrian is identified, the route is re-searched, and a new route is provided. Therefore, it is believed that the pedestrian route search system proposed in this paper will prevent negligent accidents.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.689-691
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• 2023

본 논문에서는 시작 노드와 목적지 노드 까지의 최단경로를 중점으로 가장 인접한 경유지를 선택하고 경유지가 다수일 경우 하모니서치 알고리즘을 통해 최적의 경로를 탐색하는 기법을 제안한다. 본 논문의 기법은 기존의 사용자의 현 위치에서 인접한 경유지를 추천해주는 시스템과 달리 목적지까지의 경로 전체에서 가장 인접한경유지를 선택해준다는 차별점이 있다. 그렇게 선택된 경유지들은 하모니서치 알고리즘을 사용하여 최적의 경로를 제안한다. 본 논문의 기법은 최단경로의 이탈을 최소화한 경유지 선택으로 거리, 시간, 비용적 측면에서 효율적이며 길을 헤매서 생기는 불필요한 지연을 최소화할 수 있다. 자율주행, 비행기, 선박, 드론 등 최적 경로 이탈시 큰 손실을 안기거나 위험한 시스템에 적용시 큰 효과를 거둘 수 있다.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.183-194
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• 2001

The centralized traffic information system is to gather and analyze real-time traffic information, to receive traffic information request from user, and to send user processed traffic information such as a path finding. Position information, result of destination search, and other information. In the centralized traffic information system, a server received path-finding requests from many clients and must process clients requests in time. The algorithm of multiple path-finding is needed for a server to process clients request, effectively in time. For this reason, this paper presents a heuristic algorithm that decreases time to compute path-finding requests. This heuristic algorithm uses results of the neighbor nodes shortest path-finding that are computed periodically. Path-finding results of this multiple path finding algorithm to use results of neighbor nodes shortest path-finding are the same as a real optimal path in many cases, and are a little different from results of a real optimal path in non-optimal path. This algorithm is efficiently applied to the general topology and the hierarchical topology such as traffic network. The computation time of a path-finding request that uses results of a neighbor nodes shortest path-finding is 50 times faster than other algorithms such as one-to-one label-setting and label-correcting algorithms. Especially in non-optimal path, the average error rate is under 0.1 percent.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.129-137
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• 2010

Currently used shortest path search algorithms involve graphs with vertices and weighted edges between each vertex. However, when finding the shortest path with a randomly shaped obstacle(an island, for instance) positioned in between the starting point and the destination, using such algorithms involves high memory inefficiency and is significantly time consuming - all positions in the map should be considered as vertices and every line connecting any of the two adjacent vertices should be considered an edge. Therefore, we propose a new method for finding the shortest path in such conditions without using weighted graphs. This algorithm will allow finding the shortest obstacle bypass given only the positions of the obstacle boundary, the starting point and the destination. When the row and column size of the minimum boundary rectangle to include an obstacle is m and n, respectively, the proposed algorithm has the maximum time complexity, O(mn). This performance shows the proposed algorithm is very efficient comparing with the currently used algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.74-84
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• 2010

In this paper, we propose a preference-based shortest path algorithm which is combined with Ant Colony Optimization (ACO) and A* heuristic algorithm. In recent years, with the development of ITS (Intelligent Transportation Systems), there has been a resurgence of interest in a shortest path search algorithm for use in car navigation systems. Most of the shortest path search algorithms such as Dijkstra and A* aim at finding the distance or time shortest paths. However, the shortest path is not always an optimum path for the drivers who prefer choosing a less short, but more reliable or flexible path. For this reason, we propose a preference-based shortest path search algorithm which uses the properties of the links of the map. The preferences of the links are specified by the user of the car navigation system. The proposed algorithm was implemented in C and experiments were performed upon the map that includes 64 nodes with 118 links. The experimental results show that the proposed algorithm is suitable to find preference-based shortest paths as well as distance shortest paths.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2423-2425
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• 2003

This paper proposes a decision criteria for selecting the shortest path from Dubins set between the initial and final configurations of a car-like robot. The suggested scheme is a very simple and computational savings without explicitly calculating the candidate paths and having a complicated decision table. Equations for calculating the shortest path are derived in simple form with coordinate transform and defining standard forms.